Coffee-making device with pressure control

ABSTRACT

Coffee-making device with a piston/cylinder unit, the piston ( 3 ) being driven by a crankshaft ( 11 ). A swivelling arm structure ( 13 ) is also driven by means of the crankshaft, with the interposition of a cam/cam follower mechanism. The swivelling arm structure is provided with a cover ( 19 ) for closing off the free end of the cylinder ( 2 ). The cover can be pressed onto the cylinder by means of a cam structure.

The present invention relates to a coffee-making device, comprising acoffee supply line, a hot water supply line with a pump, a beverageoutlet with shut-off valve, and a coffee outlet, said coffee-makingdevice comprises a brewing compartment for holding coffee, which brewingcompartment is connected to said water supply line and to said beverageoutlet, said brewing compartment comprising a cylinder in which a pistonis capable of reciprocating.

Such a device is known from EP 0380450A2, which discloses a structure inwhich various types of coffee can be conveyed separately from variouscontainers into the brewing compartment.

Ordinary coffee and espresso coffee have their own specificcharacteristics in the brewing process, such as, for example, thebrewing quantity, the type of coffee, the water temperature, the contacttime between coffee and water, and the pressure in the coffee bed.

If there is a desire for several brewing processes to be achieved in onebrewing system, the type of coffee and the water temperature are easy tochange for this.

It is much more difficult to switch over the pressure and the brewingquantity desired at this pressure.

It is the object of the present invention to provide a single brewingsystem by means of which it is possible to carry out different brewingprocesses. This object is achieved in a coffee-making device of the typedescribed above in that said shut-off valve is designed to provideeither a first passage with relatively small surface or a second passagewith relatively large surface, and wherein said pump is designed toprovide for an appropriate first, small volume displacement at highpressure and a second, large volume displacement at low pressure.

According to the invention, it is possible to prepare different types ofcoffee with a single coffee-making device by, apart from varying thesort and quantity of coffee, varying the throughput pressure of thewater. The latter is controlled by the shut-off valve, which can providefor various passages, and thus can regulate the pressure in the brewingsystem. All the above is, of course, also dependent upon the pump. Theterm shut-off valve can be understood to mean one or more electricallyoperated shut-off valves.

According to an advantageous embodiment of the invention, the shut-offvalve is, however, operated by the pressure of the water displaced bythe pump. To this end, the shut-off valve comprises a restriction whichreacts to pressure and is designed in such a way that at relatively lowpressure a restriction with larger passage is present and at relativelyhigher pressure a restriction with smaller passage is present.

The valve structure is designed in such a way that at relatively lowpressure a relatively large passage is present. When the pressureincreases, the passage will become smaller.

In this way it is possible, without further mechanical components and/orcontrols, to build up a higher pressure in the brewing chamber dependingon the pressure of the water that is moving through the coffee. In thisway, the pressure in the brewing chamber can be varied simply by beingcontrolled by the inlet pressure of the water. This makes it possible ina simple manner to prepare either “ordinary” coffee or espresso coffee,or variants of these.

It will be understood that the valve structure just described can alsobe used in combination with other coffee-making devices known in theprior art. After all, this valve structure is entirely independent ofthe remainder of the coffee-making devices. Of course, the fact is thatthe already simple structure of the coffee-making device is furthersimplified by using such a valve.

According to an advantageous embodiment of the invention, such astructure is used in the case of a coffee-making device comprising acylinder with piston movable therein. In this case the water supply isconnected to the volume present above said cylinder, and means forcontaining coffee are present near the free end of said cylinder. Theterm “above” in this description indicates the position away from thedrive end.

According to a further advantageous embodiment of the invention, thepiston comprises a piston head provided with a seal acting relative tosaid cylinder, an inlet channel being provided in said piston below saidpiston head, which inlet channel is sealed off relative to said cylinderand can be connected to said water supply in at least two differentpositions of said piston relative to said cylinder.

According to another advantageous embodiment, the channel is connectedby way of a non-return valve to the compartment above the cylinder.

In order to ensure that the piston functions even in the case of varyingamounts of coffee and also that the coffee-making device is of a simpledesign, according to an advantageous embodiment, provision is made for acoffee-making device comprising a housing with a cylinder in which apiston is provided, for compressing with the piston coffee placed onsaid piston, said piston being movable by means of a drive mechanism,and said drive mechanism being provided in said housing, and comprisinga cover that can be placed on said cylinder, in order to bound acompression chamber with said cylinder and piston, means for introducingwater into the compression chamber, means for discharging brewed coffeefrom the compression chamber, and also means for removing the compressedcoffee tablet, said movable cover comprising a swivelling arm structurewhich is rotatable around an axis substantially perpendicular to theaxis of said cylinder in such a way that said cover can be moved aboveand away from the end of the cylinder, which swivelling arm structure iscapable of reciprocating substantially perpendicular to the axis ofrotation thereof, in order to bring said cover into engagement in asealing manner with said cylinder end, said drive mechanism beingdesigned to operate both said piston and said swivelling arm, andcomprising a rotary input shaft, and in which said drive mechanism forsaid piston is provided with means for converting a uniform rotatingmotion into a non-uniform reciprocating motion.

The closing and opening characteristic of the piston in the cylinderunit can be influenced, in other words optimized, by converting theuniform linear rotating motion of the drive motor in some way into anon-linear motion.

Such a non-linear motion characteristic of the piston can be obtained inany way known in the prior art. An example that can be mentioned is acurved disc which is driven by the rotary motor and in turn drives thepiston. A certain opening and closing characteristic of the piston canbe obtained through the special shape of the curve.

Another possibility is to use a crankshaft structure.

In this way a particularly compact structure can be obtained with asingle drive motor. More particularly, the actual coffee-making processcan be carried out irrespective of the “tablet thickness” of the coffeematerial. This means that it is possible to vary the quantity of coffeematerial without this affecting the functioning of the device, in otherwords various types of coffee can be made with one device withoutspecial measures as regards structure being necessary.

A particularly simple structure can be obtained by using a swivellingarm structure for moving the cover on the cylinder. Owing to the factthat the swivelling arm rotates substantially about the axis of thecrankshaft, a particularly compact device is obtained.

Such a swivelling arm structure can be driven in any way known in theprior art. However, it is preferably driven by the crankshaft. If thestructure is designed in a suitable manner, it is possible for it to bedriven directly by the crankshaft, in other words without interposinggearwheels and other transmission mechanisms.

The reciprocating motion of the rocker arm in order to place the coveron the fee end of the cylinder in a sealing manner can also be carriedout in any way known in the prior art. It is, however, preferablyembodied by means of a cam/cam follower mechanism. This cam/cam followermechanism is preferably likewise fitted on the crankshaft of the piston.By this measure also, further simplification of the coffee-making deviceaccording to the invention can be obtained. The coffee-making device canconsequently be manufactured more cheaply, and fewer components willwear, and any parts that may have worn will be easier to replace.Cleaning can also be carried out in a simple manner.

The structure described above works in particular if the crankshaftrotates in different directions, in other words. It does not rotate inonly one direction during a coffee-making operation. In particular, if acombination with cams/cam followers is envisaged for driving theswivelling arm structure, such a motion in different directions isadvantageous. Of course, a corresponding, suitable control is present.

Certain parts of the motion process of the swivelling arm structure canbe controlled by means of a spring or the like.

Of course, it is the case that the already simple structure of thecoffee-making device is further simplified by using such a valve.

Further special features and details of the invention emerge from theappended drawings, in which:

FIG. 1 shows in cross section the most essential components of thecoffee-making device according to the invention;

FIG. 1a shows a detail of valve 20 from FIG. 1;

FIG. 2 shows a cross section in accordance with the line II in FIG. 1;

FIGS. 3-6 show the structure shown in FIG. 2 during various stages ofthe coffee-making process; and

FIG. 7 shows an alternative for the drive of the piston and swivellingarm structure, as illustrated in the previous figures.

Only the part of a coffee-making device according to the invention thatis essential for the invention is illustrated in the drawings. Moreparticularly, only the part by means of which the coffee is compressedand where water is conveyed through the coffee is illustrated.

The device according to the invention can be used for making bothespresso coffee and other types of coffee. However, it should beunderstood that the device can also be designed for preparing only onetype of coffee.

The device according to the invention is indicated in its entirety by 1in the figures. The device is composed of a housing (not shown in anyfurther detail), part of which is formed by a cylinder 2. A piston 3 canmove up and down inside the cylinder. Piston 3 is provided with a doubleseal. The top seal is indicated by 4, and the bottom seal is indicatedby 5. A number of windows 6 are bounded by the two seals. These windows6 can be brought into communication with a supply line 7 for warm,pressurized water. This water is provided by way of a diagrammaticallyillustrated pump 38. Windows 6 are in communication with dispensingapertures 8. The piston 3 is connected by way of piston rod 9 to a crankpin 10, which in turn forms part of a crankshaft 11, which is connectedto a motor 12, illustrated only diagrammatically. A vent valve 33, whichworks in such a way that no vacuum can arise in the confined space abovepiston 3, is present in the piston 3. In other words, only overpressurecan be produced by piston 3.

A rocker arm 13, provided with control apertures 14 and 15, is present.It can be seen from the drawing that the edge of the apertures 14, 15engages on curved discs 27, to be described further. The rocker arm 13is driven in the upward direction (in the drawing) by means of two coilsprings 18. Rocker arm 13 is provided with a cover 39 in which a filterplate 19, provided with a filter 20, is fitted.

Filter plate 19 is provided with a sealing ring 32, which interacts withthe free top end of the cylinder 2. A valve 20 is also fitted in filterplate 19. Valve 20 (FIG. 1a) is composed of an elastic bottom part 21,which can be made of, for example, a rubber-like material, and isprovided with a restriction disc 22 with a diameter of, for example, 1.0mm.

The top part of valve 20 is indicated by 23 and is composed of arelatively rigid material. An auxiliary restriction 24 and also a bypasschannel 25 are present in this top part. The valve is connected tooutlet 26 for the coffee, which in a manner not illustrated any furtheris connected to a pipe system, or in another way provides for the coffeeto pass into the cup or other storage container. The bottom part 21 inthis case is provided with a cone 34, and the top part is provided witha cone 35. When there is deformation of the bottom part 21, cones 34 and35 engage each other.

A curved disc 27, already mentioned above, is fitted on the crankshaft11. The curved disc is provided with recesses 28 and 29. The rocker arm13 is provided with a cam 30 in control apertures 14 and 15, designed toengage the curved disc 27 or its recesses.

A control indicated diagrammatically by 31 is present.

The device described above works as follows:

During a first phase of the coffee-making process (FIG. 3) the rockerarm is situated in such a position that the aperture of cylinder 2 isclear.

In this position coffee 40 is placed in a manner not illustrated in anygreater detail on the piston 3. The quantity of coffee can be dependent,for example, on the desired product: a small quantity for “ordinary”coffee, and a larger quantity for espresso coffee.

As can be seen from FIG. 3, the rocker arm 13 rests against stop 33 ofthe housing in which the device 1 according to the invention isaccommodated. Cam 30 is situated in recess 29 and, through the action ofcoil springs 18, the rocker arm is pressed upwards in the figures. Apartfrom producing a spring pressure in the upward direction, the coilsprings 18 also serve to generate a force to the left in the figures, inother words they try to move the rocker arm 13 into the position abovethe cylinder 2.

Starting from the position shown in FIG. 3, the motor 12 turns thecrankshaft 11 to the left in the view shown. During this motion thepiston 3 moves downwards, and at the same time the rocker arm 13 ismoved along with it to the left until the latter hits a stop 36 in amanner not shown in any further detail.

On further rotation of crankshaft 11 in the direction of the arrow shownin FIGS. 3 and 4, rocker arm 13 is pulled downwards. The fact is thatfurther motion to the left is impossible, on account of the stop 36, sothat on reaching the end of the recess 29 the cam 30 is presseddownwards by the curved disc, against the spring force of springs 18. Asa result, the seal 32 of filter plate 19 engages the free end ofcylinder 2.

Piston 3, driven by motor 12, which is still turning to the left, thenmoves upwards again, so that coffee 40 is compressed.

Depending on the quantity of coffee, the piston will be situated at ahigher or lower level. The “height” of chamber 6 is, however, such thatin this position the chamber 6 will always be in communication with thesupply line 7. By means of control 31, compression of the coffee 40 isestablished. In other words, if, for example, the quantity of currentsupplies to motor 12 exceeds a certain value, it is established thatsufficient compression is present and the motor is switched off, or lesscurrent is supplied to it, so that no further compression or lesscompression occurs.

Water is then supplied through line 7. This water is preferably heatedwater. Depending on the product that has to be prepared, the pressure ofthe water is selected with control 31. In other words, the output of thepump 38 is controlled by the control 31 in such a way that the desiredproduct is obtained.

For traditional coffee, a relatively low pressure will be used, whilefor espresso coffee the pressure worked with will be higher (forexample, higher than 7 atmospheres).

In both cases the warm water fed in will pass into the coffee by way ofthe chamber 6 through apertures 8, and will leave the coffee again byway of the filter plate 19, during which process the coffee is, ofcourse, retained by the filter plate. Depending on the outlet pressure,valve 20 will function. At relatively low pressure little or nodeformation of the rubber bottom part 21 will occur, in other words cone34 is not pressed against cone 35. This means that the water encountershindrance only from restriction 22, and the pressure in the coffee willremain relatively low.

If, however, water is supplied at higher pressure, this will result in agreater deformation of the bottom part 21 of valve 20, with the resultthat cones 34 and 35 seal on top of each other through deformation ofthe bottom part 21. Apart from relatively small restriction 22, theeffect of the smaller restriction 24 (for example 0.7 mm) now comes intoplay.

Because of this narrower restriction, a higher pressure will begenerated in the coffee, so that espresso can be prepared.

The coffee preparation process typically takes 10-35 seconds. After thewater has been forced through the coffee tablet, the motor 12 isswitched on again and moves in the opposite direction, as shown in FIGS.5 and 6. During this return motion the “coffee-tablet” remains adheringto the cylinder, and not to the rocker arm. The rocker arm is providedwith a scraper strip 36. The creation of vacuum between the coffeetablet and the top side of the piston is avoided by valve 33. Thisreturn motion occurs until cam 30 falls into recess 29. Owing to thespring force, rocker arm 13 moves upwards and there is no longer a sealbetween sealing edge 32 and the top end of cylinder 2. The rocker arm 13then moves along with the crankshaft 11. The stripping motion along thecoffee tablet can be carried out relatively simply. Rocker arm 13 movesto the position shown in FIG. 5 against the stop 33 of the housing. Therocker arm is then pressed downwards by the fact that crank 11 turnfurther and the “end” of recess 29 is reached. On further turning of thecrank 11, the piston 3 now moves to its top dead centre, so that thecoffee tablet 41 is moved to above the level of cylinder 2.

Cam 30 then goes into recess 28. Under the influence of coil springs 18,rocker arm 13 not only moves upwards as a result, but also shoots to theleft, as shown in FIG. 6. In the process, the coffee tablet is removedto the left by scraper strip 36. On further rotation, when there isengagement with the “end” of recess 28, cam 30, and thus rocker arm 13,is turned to the right until the initial position shown in FIG. 3 isreached.

FIG. 7 shows very diagrammatically a variant of the device describedabove. This device is indicated in its entirety by 51 and comprises acylinder 52 with a piston 53 provided therein. This piston is providedwith a rod 59, which is rigidly connected to it and provided on the endwith cams (not shown in any further detail) which run in a curved track55 of a curved disc 54. The curved disc 54 is provided with a centralshaft 56, which is driven by a central drive motor (not shown). Theswivelling arm is likewise driven by this central drive motor, in themanner described above. In this case the structure with curved disc 27and the like shown by means of the earlier figures can be used, and thelatter may be integral with curved disc 54 or otherwise.

What is claimed is:
 1. Coffee-making device (1, 51), comprising a coffeesupply line, a hot water supply line (7) with a pump, a drink outlet(26) with shut-off valve, and a coffee outlet, said coffee-making devicecomprises a brewing compartment for holding coffee, which brewingcompartment is connected to said water supply line and to said beverageoutlet, said brewing compartment comprising a cylinder in which a pistonis capable of reciprocating, characterized in that said shut-off valveis designed to provide either a first passage with relatively smallsurface or a second passage with relatively large surface, and in thatsaid pump is designed to provide an appropriate first, small volumedisplacement at high pressure and a second, large volume displacement atlow pressure.
 2. Coffee-making device according to claim 1, in whichsaid shut-off valve comprises a restriction which reacts to pressure,and is designed in such a way that at relatively low pressure arestriction with larger passage is present and at relatively higherpressure a restriction with smaller passage is present.
 3. Coffee-makingdevice according to claim 1, in which said shut-off valve comprises twoelectrically controllable valves.
 4. Device according to claim 1, inwhich said brewing compartment comprises a cylinder in which a piston iscapable of reciprocating.
 5. Coffee-making device according to claim 4,comprising a cylinder with piston movable therein, in which said watersupply is connected to the volume present above said cylinder, and meansfor containing coffee are present near the free end of said cylinder. 6.Coffee-making device according to claim 5, in which said pistoncomprises a piston head provided with a seal (4) which works relative tosaid cylinder, an inlet channel (6) being provided in said piston belowsaid piston head, which inlet channel is sealed off relative to saidcylinder and can be connected to said water supply line (7) in at leasttwo different positions of said piston relative to said cylinder. 7.Coffee-making device according to claim 6, in which said inlet channelis connected by way of a non-return valve (33) to the compartment abovesaid cylinder.
 8. Coffee-making device (1) according to claim 1,comprising a housing with a cylinder (2) in which a piston (3) isprovided, for compressing with the piston coffee placed on said piston,said piston being movable by means of a drive mechanism (10, 11) andsaid drive mechanism being provided in said housing, and comprising acover (39) that can be placed on said cylinder, in order to bound acompression chamber with said cylinder and piston, means for introducingwater into the compression chamber, means for discharging brewed coffeefrom the compression chamber, and also means for removing the compressedcoffee tablet, said movable cover comprising a swivelling arm structure(13) which is rotatable around an axis substantially perpendicular tothe axis of said cylinder in such a way that said cover can be movedabove and away from the end of the cylinder, which swivelling armstructure is capable of reciprocating substantially perpendicular to theaxis of rotation thereof, in order to bring said cover into engagementin a sealing manner with said cylinder end, said drive mechanism beingdesigned to operate both said piston and said swivelling arm andcomprising a rotary input shaft, characterized in that said drivemechanism for said piston is provided with means for converting auniform rotating motion into a non-uniform reciprocating motion. 9.Coffee-making device according to claim 8, in which said means comprisea rotating curved disc and engagement means connected to the piston andengaging upon the curve of said disc.
 10. Coffee-making device accordingto claim 8, in which said means comprise a crankshaft, in which the axisof rotation of said swivelling arm structure comprises the axis of saidcrankshaft, and in which said piston is connected to the driving rod ofsaid crankshaft.
 11. Coffee-making device according to claim 10, inwhich said swivelling arm structure (13) can be driven by saidcrankshaft.
 12. Coffee-making device according to claim 8, in which acam/cam follower mechanism is present for transmitting saidreciprocating motion.
 13. Coffee-making device according to claim 9, inwhich said cam or cam follower is fitted on said crankshaft and said camfollower or cam is fitted on said swivelling arm structure. 14.Coffee-making device according to claim 8, comprising spring means fordriving said swivelling arm structure into the position above the freeend of said cylinder.
 15. Coffee-making device according to claim 8, inwhich said swivelling arm structure is provided with means (36) fordischarging said coffee tablet.
 16. Coffee-making device according toclaim 8, in which said drive mechanism is designed to rotate in twodirections.